South Africa’s municipalities treat approximately 7.5 million cubic meters of effluent on a daily basis. The operating costs to treat the effluent exceed R3 billion per annum and the capital replacement cost of the installed treatment capacity would be close to R40billion. Larger WWTWs (in general) have a better skills base, use advanced treatment processes and have access to the necessary resources to optimally operate their WWTWs while smaller don’t often have the necessary skills to operate and maintain the plants and the necessary funds to refurbish and optimise processes to stretch capacity. Plant capacity is also a major factor of concern in South Africa. Many works are receiving inflows that are at or exceed their design capacities. The cost associated with increasing the treatment capacity at WWTWs is between R4mn to R10mn per megalitre per day (MLD) of treatment capacity and the operating costs are between R0.5 and R1.5/kl treated. With estimates thus running into tens of billions of rands to address the plant capacity constraints and limited skills at smaller and rural WWTW’s to deal with O&M, less capital intensive and more robust solutions are sought. If carbon loading is the capacity constraint, it is possible to increase the total plant capacity by as much as 30% due to higher nutrient removal in the primary settlers. A treatment process similar to chemically enhanced primary treatment (CEPT), may offer rural communities a simpler and more robust treatment addition.
The product that is most widely used for CEPT is Ferric Chloride (Ferric). However, both laboratory and plant scale testwork has shown that biological flocculants also have the potential to assist and in some cases simplify the CEPT processes. Where viable, the cultivation and processing of biological flocculants may also enable rural communities to retain scarce currency within their communities, create opportunities for rural development and help these communities become financially self sufficient with regard to their sanitation needs. There are many biological products that have proven flocculation capabilities. These include Moringa seeds, Chitosan, Tannins, Fenugreek, Opuntia, Peach seed kernels, Beans, Rice and Maize. All of these products are cultivated (or available as waste products) in South Africa.